While the use of fluid supply and radiant heating apparatus within drying and curing systems are quite well-known, conventional systems employing such apparatus have significant disadvantages, the primary disadvantage being inefficiency. This operational defect, in turn, renders such conventional systems impractical, economically unfeasible, and commercially unacceptable. In addition, the quality of the work products is also often deleteriously affected.
The inefficiency of such conventional systems probably manifests itself best in the form of poorly defined fluid flow paths within the various systems. For example, the absence of effective exhaust facilities within the systems leads to the development of stagnant boundary layer conditions within the vicinity of the substrate. Such conditions substantially impede the evolution of the volatile constituents from the substrate. In addition, such conditions materially interfere with the transfer of energy from the radiant energy sources to the substrate. As a result, the drying process proceeds at an unacceptably low rate whereby the drying process time must be increased. In view of the fact that the substrates are normally transported along suitable conveying means throughout the system during the drying process, additional system layout area is required.
Similarly, the prior art systems do not provide for the flashing off of a substantial portion of the volatile constituents comprising, for example, water or solvent base coatings. As a result, an appreciable portion of such constituents may be absorbed within the substrate and subsequently trapped therein in view of subsequent drying or curing process steps. Substantial absorption of these constituents into the substrate causes imperfections therein, such as, for example, streaking, distortion, deformation, and the like.
Still further, in conjunction with the aforenoted exhaust facilities and flashing apparatus, proper facilities are also required in order to recirculate the treating fluid within the system. This is likewise of paramount importance from an efficiency and energy conservation viewpoint in view of the fact that the spent treating fluid has a substantial amount of heat embodied therein. The heat level of such air is to be properly maintained in view of the drying processes to be achieved, however, fresh ambient air must also be supplied into the system in order to provide sufficient cooling for the radiant energy source reflectors as well as to modify the volatile constituent level within the recirculated fluid. In conjunction with such fluid control characteristics, controlled exhaust means must likewise be provided in order to exhaust a predetermined percentage of the recirculated air.